1. Field of the Invention
This invention relates to the field of dentistry and more specifically to work support apparatus having guide and positioning means.
2. Description of the Prior Art
The devices and techniques used thus far in the art of dental impression handling tools and the like have required a mold process to be performed by a dental technician. Various types of devices/procedures have been used, with all of them generally falling into three categories.
The first, and most widely used type of device/procedure, involves the use of some form of positioning pins or rods which are inserted into the molds, with the molds then being positioned on a base. The base is most generally made of the same material as the mold. This method is time consuming and relatively difficult to perform. Some of the steps which may be required in order to construct a model are: Drilling the model, pouring a plaster base, inserting pin sleeves into the base material before hardening, and repairing the model due to sawing into improperly placed pins.
The second type of device/procedure involves pouring mold material into a negative impression, and a pre-formed base, or mold, form having a channel or indented cavity. In this method, the mold material is cast so as to form an indexing pattern. Once the mold has hardened, it is removed from the form base so that saw cuts can be made in the model. The model is then re-assembled into the pre-formed base. While this method requires less time than the previously-described method, the accuracy of indexing deteriorates with each removal and re-insertion of the model into the pre-formed base, and attachment of the model to the base requires either a manual locking mechanism, or a chemical application.
Both of these first two types of devices/procedures have the added disadvantage of having to "construct" the "bite" after the opposing jaw models have been removed from the negative impression.
The third type of device/procedure generally incorporates a base and a set of pre-established positioning element(s). The positioning element(s) fit into the base by using rods, or tabs, that protrude from the underside of the positioning element(s), and fit into holes or slots in the base. While this arrangement takes less casting time and provides more consistent alignment, it has some significant drawbacks. Generally, this arrangement requires that either the negative impression be precisely aligned to the positioning elements at the time of mold casting, or that the mold be chemically attached to the positioning elements after the mold has been removed from the negative impression. Devices that do not require either of the above require the mold to be removed from the base in order to permit sawing through the mold.
All of the prior art arrangements require that the methods thereof be performed by a skilled technician in order for the device/procedure to function properly.